[Intel-gfx] [RFC PATCH 05/12] drm/i915/dsi: remove unnecessary dsi device callbacks

[Daniel Vetter]

On Fri, Jan 23, 2015 at 03:14:41PM +0530, Shobhit Kumar wrote:
> On 01/22/2015 06:53 PM, Jani Nikula wrote:
> >On Thu, 22 Jan 2015, Shobhit Kumar <shobhit.kumar at linux.intel.com> wrote:
> >>There had been a instance where we had to drive different resolution
> >>(lower) than the native one. Also in VBT there is a field to make this
> >>generic at least from driver perspective to give the needed target
> >>resolution. In case target resolution is same as native, nothing gets
> >>changed, else mode_fixup function adjusts the mode accordingly keeping
> >>timing as same and enabling scalar. Might not be useful in general, but
> >>did find a use internally.
> >
> >Can we just have the driver return the desired mode from .get_modes in
> >that case?
> 
> Okay, I think I did not explain correctly. Get modes is modified to give the
> needed target mode only so that userspace creates buffer of the needed
> resolution, but in fixup which is called at modeset, we correct the
> adjusted_mode back to have native resolutions so that modeset is correctly
> done. if we do not do like this, during modeset resolutions will be wrong as
> per the timings.

I'm confused. Can you please give an example in real numbers about the
different resolution and how it's all fixed up in hw?

E.g. 800x600 framebuffer -> pfit -> 1024x756 panel,

get_modes gives 800x600, adjusted mode corrects to 1024x756. And please
mention what vbt has to do in all this too.

I think I need an example since I can't figure out what exactly your
describing ...

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch